Structure material and molded product using the same and decomposing method thereof

ABSTRACT

A structure material of the present invention consisting essentially of 20 parts by weight or more of a polymer mixture consisting essentially of of a thermoplastic aromatic polyester and a thermoplastic aliphatic polyester on the basis of 100 parts by weight of the structure material. The polymer mixture comprises 3 to 40 parts by weight of the aliphatic polyester on the basis of 100 parts by weight of the polymer mixture.

TECHNICAL FIELD

The present invention relates to a structure material and a moldedproduct using the structure material and a decomposing method for such amolded product. More specifically, the present invention relates to astructure material which has excellent mechanical strength and heatresistance and is easily decomposed at the time of disposal and a moldedproduct using such structure material, and a decomposing method thereof.

BACKGROUND ART

In recent years, global environmental issues have been greatly paidattention to. In particular, regarding resin waste, it is desired: (1)to collect and recycle valuable substances from waste in order to avoiddepletion of resources; and (2) to reduce the volume of waste to dealwith a reduced space for burying refuse. However, the reduction involume of the resin waste has hardly been promoted, and the resin wasteis generally treated by burning.

Regarding a resin molded product, a molded product obtained byintegrally molding a structure material together with at least a metal(e.g., a molded product such as a molded motor and molded transformer; arecording medium such as a magnetic tape, a magnetic disc and anopto-magnetic disc) are utilized in consumer equipment, industrialequipment, office equipment or the like. Taking a molded motor as anexample, the demand for molded motors has rapidly expanded because oftheir excellent properties in terms of noise, damping, insulation andmaintenance, and teir compact size facilitates automation thereof.

Conventionally, a molded stator of a molded motor used as an alternatecurrent motor, a brushless direct current motor or the like generallyhas a structure disclosed in Japanese Laid-Open Patent Publication No.61-214740. The structure will be described with reference to FIGS. 5 and6. FIG. 5 is a perspective view showing an external appearance of amolded motor having a conventional molded stator 201. FIG. 6 is aperspective view showing the structure of a stator section before beingmolded. As shown in FIG. 5, the molded motor has a motor section 220 anda molded stator 201 which is integrally molded so as to cover the statorsection of FIG. 6 with a molding compound 202. As shown in FIG. 6, thestator section has an iron core 204 wound by a wire 203 via acylindrical insulator 207. The insulator 207 has a printed board 211having a wiring pattern 210 at a part of its circumference at one endthereof. The terminal portion of the wire and a lead line 212 areconnected on the printed board 211, and an external signal is input tothe coil. The molding compound contains a thermoplastic resin such aspolyethylene terephthalate, polyethylene, polypropylene and nylon, or athermosetting resin such as an unsaturated polyester resin, a vinylesterresin and a phenol resin as a binder, and further contains calciumcarbonate, talc, carbon black or the like as an additive.

It is desirable at the time of disposal of the molded motor to removethe molding compound and recycle metals such as the iron core and thewires which are valuable. In conventional waste treatment, generally,the molding compound is crushed by a shredder at first, and thenvaluable substances such as the iron core and the wire are recoveredfrom the debris for recycle. However, in such a structure of the moldedmotor, the iron core and the wire easily cause damage to the teeth ofthe shredder. Therefore, such a crushing treatment is not favored, andthe valuable substances are disposed of without being recycled and thenburied in the earth with other waste. Since the aforementioned moldingcompound is not naturally decomposed while being buried, a silicon steelplate or a copper wire used in the iron core and the wire are left inthe land without being recycled, in spite of their high value as anafter use material. In addition, since the reduction in volume of themolding compound has not been promoted, it becomes difficult to ensurespace for burying it.

In the case where the molding compound contains a thermoplastic resinsuch as polyethylene terephthalate as the main component, polyethyleneterephthalate can be dissolved in a mixing solvent of chlorophenol ormetacresol and tetrachloroethane. Therefore, it is theoreticallypossible to remove such a molding compound by dissolving it in thesolvent. However, the dissolution in the solvent takes an extremely longtime. Moreover, such a mixing solvent is so toxic that the use thereofis restricted. In addition, in view of recent environmental issues, theuse of such a solvent is out of the question. Therefore, in theconventional molded motor, the molding compound cannot be crushed,decomposed, dissolved nor reduced in volume, and thus poses the problemthat it is difficult to recycle valuable substances such as the ironcore and the wire at the time of disposal.

Regarding the molded product obtained by molding a structure materialand a metal, other molded products such as a molded transformer and amagnetic tape have the same problems as the molded motor as describedabove.

As described above, in view of the decomposition and the reduction involume of resin waste and recycle of valuable substances, a structurematerial which is readily decomposed while maintaining excellentcharacteristics of conventional structure materials is desired.

DISCLOSURE OF THE INVENTION

A structure material of the present invention comprises 20 parts byweight or more of a polymer mixture of a thermoplastic aromaticpolyester and a thermoplastic aliphatic polyester on the basis of 100parts by weight of the structure material. The content of thethermoplastic aromatic polyester in the polymer mixture is larger thanthe content of the thermoplastic aliphatic polyester.

In one preferred embodiment, the polymer mixture can be decomposed intoa monomer unit by a decomposing solution containing a base and ahydrophilic solvent.

In one preferred embodiment, the mixture comprises 3 to 40 parts byweight of the aliphatic polyester on the basis of 100 parts by weight ofthe mixture.

In one preferred embodiment, the aliphatic polyester is at least oneselected from the group consisting of polycaprolactone, polycaprolactonediol, polycaprolactone triol, polyethylene succinate, polybutylenesuccinate and polylactic acid.

The molded product of the present invention is formed of the structurematerial described above.

In one preferred embodiment, the molded product of the present inventionis a recording medium including a substrate formed of the structurematerial and a recording layer provided on the substrate.

In one preferred embodiment, the molded product of the present inventionis selected from the group consisting of a magnetic tape, a magneticdisc, an opto-magnetic disc and a phase change type optical disc.

In one preferred embodiment, the molded product of the present inventionis formed by molding the structure material together with at least ametal.

In one preferred embodiment, the molded product of the present inventionis a molded motor having a molded section formed of the structurematerial integrally molded containing the metal. The structure materialcontains an inorganic filler.

In one preferred embodiment, the molded section includes an internalmolded section covering the metal and an external molded section whichis provided outside the internal molded section and whose outermostportion defines an outermost portion of the molded product. The internalmolded section is formed of the structure material. The external moldedsection is formed of a molding compound containing a thermosettingresin.

In one preferred embodiment, the molded product of the present inventionis a molded motor having a molded section formed of the structurematerial integrally molded containing the metal and an insulator. A partof the insulator penetrates the molded section and is exposed flush withthe surface of the molded section.

In one preferred embodiment, the molded section is formed of a moldingcompound containing a thermosetting resin. The insulator comprises 20parts by weight or more of a polymer mixture of a thermoplastic aromaticpolyester and a thermoplastic aliphatic polyester on the basis of 100parts by weight of the insulator. The aliphatic polyester is at leastone selected from the group consisting of polycaprolactone,polycaprolactone diol, polycaprolactone triol, polyethylene succinate,polybutylene succinate and polylactic acid.

A decomposing method for a structure material of the present inventionincludes the step of immersing the structure material in a decomposingsolution containing a base and a hydrophilic solvent at a temperaturelower than the boiling point of the hydrophilic solvent. The structurematerial comprises 20 parts by weight or more of a mixture of athermoplastic aromatic polyester and a thermoplastic aliphatic polyesteron the basis of 100 parts by weight of the structure material, and thecontent of the thermoplastic aromatic polyester in the mixture is largerthan the content of the thermoplastic aliphatic polyester.

A decomposing method for a molded product of the present invention is adecomposing method for a molded product formed by molding a structurematerial together with at least a metal. The structure materialcomprises 20 parts by weight or more of a mixture of a thermoplasticaromatic polyester and a thermoplastic aliphatic polyester on the basisof 100 parts by weight of the structure material, and the content of thethermoplastic aromatic polyester in the mixture is larger than thecontent of the thermoplastic aliphatic polyester. The method includesthe steps of immersing the molded product in a decomposing solutioncontaining a base and a hydrophilic solvent at a temperature lower thanthe boiling point of the hydrophilic solvent, and decomposing at least apart of the structure material forming the molded product and thenseparating and collecting the metal.

In one preferred embodiment, the hydrophilic solvent is a mixed solventof water and lower alcohol.

In one preferred embodiment, the separation and the collection of themetal are performed in a state where the structure material remainsmoist.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross sectional view showing an embodiment of amolded motor as an example of a molded product of the present invention.

FIG. 2 is a cross sectional view of a primary part of another embodimentof a molded motor as an example of a molded product of the presentinvention.

FIG. 3 is a cross sectional view of a primary part of still anotherembodiment of a molded motor as an example of a molded product of thepresent invention.

FIG. 4 is a schematic partial cross sectional view of a magnetic tape asan example of a molded product of the present invention.

FIG. 5 is a perspective view showing an external appearance of aconventional molded motor.

FIG. 6 is a perspective view showing an appearance of a stator sectionof the conventional molded motor.

BEST MODE FOR CARRYING OUT THE INVENTION

A. Structure Material

A thermoplastic aromatic polyester used in a structure material of thepresent invention is obtained by condensation-polymerizing aromaticpolybasic acid and glycol by a known method. Typical examples of thethermoplastic aromatic polyester include polyethylene terephthalaterepresented by Formula (I), polybutylene terephthalate represented byFormula (II), polycyclohexane terephthalate represented by Formula (III)and polybutylene naphthalate represented by Formula (IV).

Examples of the aromatic polybasic acid include phthalic anhydride,isophthalic acid, terephthalic acid, diphenyl carboxylic acid. They canbe used singularly or in combination thereof. Isophthalic acid ispreferable because of its low cost and its excellent strength, andterephthalic acid is preferable because of its exceptional strength.

Examples of the glycol include ethylene glycol, propylene glycol,diethylene glycol, dipropylene glycol, neopentyl glycol, hexamethyleneglycol, polyethylene glycol, butanediol. They can be used singularly orin combination thereof. Ethylene glycol is preferable because of its lowcost, and butanediol is preferable because of its high crystallinity andresulting excellent strength.

Exemplary examples of a specific combination of an aromatic polybasicacid and glycol are as follows: isophthalic acid and ethylene glycol;isophthalic acid and butanediol; and terephthalic acid and butanediol.

The thermoplastic aliphatic polyester used in the structure material ofthe present invention can be easily decomposed in a decomposing solutioncontaining a base and a hydrophilic solvent described later. Examples ofthe aliphatic polyester include a polymer obtained by ring-openingpolymerization of lactone such as polycaprolactone and polypropiolactonerepresented by Formula (V); a polymer of hydroxylic acid such aspolylactic acid represented by Formula (VI) and polyglycol acidrepresented by Formula (VII); a polymer having a functional group in itsterminal such as polycaprolactone diol represented by Formula (VIII) andpolycaprolactone triol represented by Formula (IX); a copolymer ofglycol and aliphatic dicarboxylic acid represented by Formula (X); andpoly(3-hydroxyalkanoate) obtained by fermentation of microorganism suchas poly(3-hydroxypropionate), poly(3-hydroxybutylate),poly(3-hydroxyvalerate), poly(3-hydroxyoctanoate) or the like.

where R¹ and R² are independently a hydrocarbon group having 1 to 20carbon atoms, and n¹ and n² are independently an integer of 1 to 6.

Specific examples of the copolymer represented by Formula (X) includepolybutylene succinate, polyethylene malonate, polyethylene succinate,polyethylene adipate, polyethylene pimelate, polyethylene suberate,polyethylene azelate, polyethylene sebacate, polyethylene decamethylate,polytetramethylene succinate, polypentamethylene succinate,polyhexamethylene succinate, polytrimethylene adipate,polytetramethylene adipate, polyhexamethylene adipate, polytrimethylenesebacate, polytetramethylene sebacate, polyhexamethylene sebacate,polyethylethylene succinate, poly-1,2-dimethylethylene succinate,polyethylethylene adipate, polymethylethylene sebacate,poly-1-methyltrimethylene succinate, poly-2,2-dimethyltrimethylenesuccinate, poly-1-methyltrimethylene adipate,poly-2,2-dimethyltrimethylene adipate, poly-1-methyltrimethylenesebacate, poly-2,2-dimethyltrimethylene sebacate, and a copolymer ofε-caprolactone, adipic acid and hexamethylenediol.

Among the thermoplastic aliphatic polyesters, polycaprolactone,polycaprolactone diol, polycaprolactone triol, polybutylene succinateand polylactic acid are preferable, because of their excellentdecomposability and easy industrial production. Polycaprolactone andpolylactic acid are especially preferable, because of theirdecomposability.

A polymer mixture of the thermoplastic aromatic polyester and thethermoplastic aliphatic polyester can be decomposed into a monomer unitby a decomposing solution containing a base and a hydrophilic solventdescribed later.

In the polymer mixture, the content of the thermoplastic aromaticpolyester is larger than that of the thermoplastic aliphatic polyester.In the case where the content of the thermoplastic aromatic polyester issmaller than that of the thermoplastic aliphatic polyester, it is likelythat the mechanical strength of the obtained structure material isinsufficient. Furthermore, since the obtained structure material iseasily hydrolyzed, it is likely to be difficult to use at a highhumidity. More specifically, the content of thermoplastic aliphaticpolyester in the polymer mixture is preferably 3 to 40 parts by weight,more preferably 10 to 30 parts by weight, and most preferably 10 to 25parts by weight on the basis of 100 parts by weight of the mixture. Inthe case where the content of the thermoplastic aliphatic polyester isbelow 3 parts by weight, it is likely that the decomposability of theobtained structure material (e.g., a decomposing rate and the degree ofdecomposition into a monomer unit) is insufficient.

In the polymer mixture contained in the structure material of thepresent invention, particularly preferred examples of the combination ofthe thermoplastic aromatic polyester and the thermoplastic aliphaticpolyester are as follows: polyethylene terephthalate andpolycaprolactone (weight ratio 85:15); polyethylene terephthalate andpolylactic acid (weight ratio 80:20); polyethylene terephthalate andpolybutylene succinate (weight ratio 85:15); polybutylene terephthalateand polylactic acid (weight ratio 80:20); and polybutylene terephthalateand polybutylene succinate (weight ratio 85:15).

The structure material of the present invention contains theabove-mentioned polymer mixture in an amount of preferably 20 parts byweight or more, preferably 30 parts by weight or more, and morepreferably 40 parts by weight or more on the basis of 100 parts byweight of the structure material. In the case where the content of thepolymer mixture is below 20 parts by weight, it is difficult for adecomposing solution to permeate into the structure material. As aresult, it is likely that the decomposition and the reduction in volumeof the structure material takes too much time.

The structure material can optionally further contain a releasing agent,wax, a coloring agent, a thickener, a filler or the like.

Examples of the releasing agent include stearic acid, zinc stearate,calcium stearate or the like.

Examples of the wax include Hoechst wax, carnauba wax, paraffin or thelike.

Examples of the coloring agent include titanium white, chromium oxide,carbon black or the like.

Examples of the thickener include beryllium oxide, magnesium oxide,magnesium hydroxide, calcium oxide, calcium hydroxide, zinc oxide,benzoic acid, phthalic anhydride, tetrahydrophthalic anhydride, maleicanhydride or the like.

Examples of the filler include an inorganic filler, for example,carbonate such as calcium carbonate and magnesium carbonate, sulfate orsulfite such as calcium sulfate, barium sulfate and calcium sulfite,silicate such as clay, mica, glass balloon, montmorillonite, silicicacid, kaolin, talc, oxides such as silica, diatomaceous earth, ironoxide, pumice balloon, titanium oxide and alumina, hydroxides such asaluminum hydroxide and magnesium hydroxide, graphite, glass fibers,carbon fibers and asbestos fibers; and an organic filler, for example,wood powder, grain fibers such as chaffs, cotton, paper stripes, nylonfibers, polyethylene fibers, lumber, pulp, cellulose or the like.

In the case where a lightweight molded product requiring operability isdesired, polyethylene fibers are preferably used. The structure materialcomprising polyethylene fibers as a filler has exceptional specificstrength and specific elastic modulus in view of light weight.

The filler is added in a range of, preferably more than 0 to 80 parts byweight, more preferably 20 to 70 parts by weight, and most preferably 30to 60 parts by weight, on the basis of 100 parts by weight of thestructure material. By adding the filler in such a range, the mechanicalstrength of the structure material is improved. Furthermore, since thethermoplastic aliphatic polyester is sufficiently dispersed in thestructure material, permeability of the decomposing solution is improvedand the structure material having an excellent decomposability can beobtained.

Furthermore, the structure material of the present invention cancomprise a thermoplastic resin other than the aforementioned polyesters(i.e., the thermoplastic aromatic polyesters and the thermoplasticaliphatic polyesters). Examples of such a thermoplastic resin includepolyethylene, polypropylene, polystyrene, polyvinyl acetate,polymethylmethacrylate, poly(ethylene vinyl alcohol), an acryliccopolymer, a methacrylic copolymer, a styrene-butadiene block copolymer,acrylonitrile-butadiene-styrene copolymer. The content and the type ofthese thermoplastic resins can be suitably changed depending on adesired characteristic of the structure material.

The structure material can be formed by injection molding, transfermolding, compression molding, inflation, casting or the like.

Known conditions can be applied to the molding conditions. For example,in the case of the injection molding, the conditions of a cylindertemperature of 250° C., a mold temperature of 100° C., and an injectionpressure of 700 kg/cm² are preferable.

As described below, the structure material of the present invention canbe formed into a variety of molded products. Furthermore, since thestructure material itself has excellent decomposability, the structurematerial of the present invention can be used for fiber reinforcedplastic (FRP), sheet molding compound (SMC) or the like for the purposeof volume reduction and collecting a filler (e.g., glass fibers andinorganic particles), in addition to specific molded products.

B. Molded Product

The molded product of the present invention can be formed by using thestructure material of the present invention. Specific examples of themolded product include a molded article (e.g., a molded motor, a moldedstator, a molded transformer); a general electric parts (e.g., adeflecting yoke of a TV, a reflecting plate of a lamp, a connector, ahousing of a relay and switches); an automobile molded product (e.g., abumper, a clutch box, an instrument panel); a recording medium (e.g., amagnetic tape, a magnetic disc, an opto-magnetic disc, a phase changetype optical disc); and a general resin molded product (e.g., a plasticcontainer, a cartridge of a magnetic tape). Preferably, the moldedproduct of the present invention is a molded product containing a metalwhich is a valuable substance. Specific examples of the metals containedin the molded product include copper, iron, aluminum, acobalt-phosphorus alloy, a cobalt-nickel alloy, chromium dioxide, cobaltmodified iron oxide and nickel.

Hereinafter, preferred examples of the molded product of the presentinvention will be described. However, the molded product of the presentinvention is not limited to any of the examples below.

Preferred embodiments will be described with reference to theaccompanying drawings by taking a molded motor as an example of themolded product of the present invention.

A preferred embodiment of a molded motor will be described withreference to FIG. 1. FIG. 1 is a cross sectional view showing anembodiment of a molded motor of an exemplary molded product of thepresent invention. The molded motor includes a motor section 101 and amolded stator 1. The molded stator 1 includes an iron core 4, a wire 3winding round the iron core 4, and a molded section 2 formed of astructure material integrally molded with the iron core 4 and the wire3. The outermost portion of the molded section 2 defines the outermostportion of the molded stator 1. The motor section 101 is provided at anopening of the molded section 2, and includes at least a rotating shaft102 and a rotator 103 attached to the rotating shaft 102. The motorsection 101 is supported by a bracket 104. The rotator 103 is axiallysupported by a bearing 105 provided in an upper wall of the opening anda bearing 106 provided in the bracket. Although it is not shown, the endportion of the wire 3 extends to a portion above the shaft of the moldedstator, and is connected to a lead wire there. Thus a signal can beinput through the lead wire. The molded stator 1 may be further providedwith a flange section 5 having a plurality of provision bores 6.

The aforementioned structure materials can be used for the moldingcompound constituting the molded section 2.

The maximum thickness of the molded section can be varied depending onthe use, but is preferably 0.1 to 20 mm, more preferably 0.2 to 10 mm,and most preferably 0.2 to 5 mm in the present invention.

Another preferred embodiment of a molded motor will be described withreference to FIG. 2. FIG. 2 is a cross sectional view of a primary partof a molded motor of this embodiment. Hereinafter, in the figures, likereference numerals correspond to like components. More specifically, thenumber of units in reference numerals in FIGS. 2 and 3 is identical withthe number of corresponding components in FIG. 1, and the number of tensrepresents the figure number.

This embodiment shows the case where the molded section 22 includes aninternal molded section 22 a and an external molded section 22 b. Asshown in FIG. 2, the molded stator 21 includes an iron core 24, aninsulator 27 covering at least a part of the iron core 24, a wire 23winding round the iron core 24 and the insulator 27, and the moldedsection 22 made of a molding compound integrally molded with the ironcore 24, the insulator 27 and the wire 23. The molded section 22includes the internal molded section 22 a covering at least a part ofthe iron core 24 and the external molded section 22 b which is providedoutside the internal molded section 22 a and whose outermost portiondefines the outermost portion of the molded stator 21.

The maximum thickness of the external molded section can be varieddepending on the use, but is preferably 0.1 to 20 mm, more preferably0.2 to 10 mm, and most preferably 0.2 to 5 mm in the present invention.

The thickness of the internal molded section can also be varieddepending on the use, as with the external molded section, but ispreferably 0.5 to 10 mm, more preferably 1 to 7 mm, and most preferably2 to 5 mm in the present invention.

The internal molded section 22 a is formed of the aforementionedstructure material.

The external molded section 22 b is formed of a thermosetting (orphotocurable) molding compound containing a thermosetting resin. Thethermosetting resin is not particularly limited, as long as it issuitable for the intended purpose. Typical examples thereof include anunsaturated polyester resin, a vinyl ester resin and a phenol resin. Thecase of an unsaturated resin will be only described herein.

The unsaturated polyester can be obtained by a known condensationpolymerization of unsaturated polybasic acid and saturated polybasicacid and glycol. Examples of the unsaturated polybasic acid includemaleic anhydride, fumaric acid, itaconic acid and citraconic acid.Examples of the saturated polybasic acid include phthalic anhydride,isophthalic acid, terephthalic acid, adipic acid, sebacic acid,tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride,endomethylene tetrahydrophthalic anhydride, chlorendic acid andtetrabromophthalic anhydride. Examples of the glycol include ethyleneglycol, propylene glycol, diethylene glycol, dipropylene glycol,neopentyl glycol, 1,3-butanediol, 1,6-hexanediol, bisphenol A hydride, abisphenol A propylene oxide and dibromoneopentyl glycol.

Examples of the preferred unsaturated polyester include a copolymer ofisophthalic acid and fumaric acid and neopentyl glycol represented byFormula (XI), a copolymer of phthalic anhydride and fumaric anhydrideand propylene glycol represented by Formula (XII) and a copolymer ofisophthalic acid and maleic anhydride and propylene glycol representedby Formula (XIII).

Preferably, the molding compound forming the external molded section cansuitably contain a curing agent, an addition-polymerizable monomer and alow shrink agent or the like other than the aforementioned additiveswhich can be added to the structure material.

Examples of the curing agent include benzoyl peroxide,t-butylperbenzoate, t-butylperoxybenzoate, t-butylperoxylaurate,t-butylperoxy-2-ethylhexanoate, t-butylperoxyoctoate, or the like.

Examples of the addition-polymerizable monomer include styrene, vinyltoluene, a-methylstyrene, methyl methacrylate, vinyl acetate,diallylphthalate, diallylisophthalate, diallyltetrabromophthalate,phenoxyethyl acrylate, 2-hydroxyethyl acrylate, 1,6-hexanedioldiacrylate or the like.

Examples of the low shrink agent include a thermoplastic resin such aspolyethylene, polypropylene, polystyrene, polyvinyl acetate, polymethylmethacrylate, poly(ethylene vinyl alcohol), an acrylic copolymer, amethacrylic copolymer, a styrene-butadiene block copolymer, and anacrylonitrile-butadiene-styrene copolymer.

A thermoplastic resin such as a thermoplastic aliphatic polyester, athermoplastic aromatic polyester and polyethylene can be used for theinsulator 27. Since the insulator 27 requires a shape preservationeffect of the wire 3 during molding, it is preferable to use a materialhaving a softening point or a melting point above the temperature at thetime of molding, e.g., about 100° C. or more, so that the insulator isnot softened during molding. Furthermore, the molding temperature of theinternal molded section is preferably equal to or lower than thetemperature at which the insulator 27 is deformed. It is especiallypreferable to use a polymer mixture of a thermoplastic aliphaticpolyester and a thermoplastic aromatic polyester or a thermoplasticaliphatic polyester for the insulator 27, because it is possible toseparate the wire 23 and the iron core 24 during decomposition. In thecase where a polymer mixture of a thermoplastic aliphatic polyester anda thermoplastic aromatic polyester is used, by using a thermoplasticaliphatic polyester having a melting point exceeding 100° C., themelting point of the entire mixture exceeds 100° C. Therefore, it ispossible to select a thermoplastic aromatic polyester in a wide range.An example of the aliphatic polyester having a melting point exceeding100° C. is a copolymer resin represented by Formula (X).

Alternatively, the external molded section 22 b is formed of athermoplastic molding compound containing only a thermoplastic aromaticpolyester as a binder.

The molded motor of this embodiment having the above-mentionedconfiguration has advantages over the molded motor shown in FIG. 1because of its environmental stability. For example, such a molded motoris stable in a high temperature and high humidity condition wherealiphatic polyester is readily decomposed, and thus is usable in such acondition. Furthermore, such a molded motor has exceptional mechanicalstrength.

In decomposing the molded motor of this embodiment having such aconfiguration, before immersing the molded motor in a decomposingsolution, the internal molded section is preferably exposed so as to bein contact with the decomposing solution. This is because the externalmolded section is not easily decomposed by the decomposing solution. Theexposure of the internal molded section can be performed by scratchingwith a saw, a chisel or the like, or by opening with a drill. Afterimmersing the molded motor in the decomposing solution, the internalmolded section is decomposed so as to form a hollow portion in theinside of the molded section. Therefore, metals can be easily separatedand collected.

Still another preferred embodiment of a molded motor of an exemplarymolded product of the present invention will be described with referenceto FIG. 3. FIG. 3 is a cross sectional view showing a primary part of amolded motor of this embodiment.

This embodiment shows the case where a part of an insulator 37 isexposed flush with the surface of an external molded section 32 b. Asshown in FIG. 3, a molded stator 31 includes an iron core 34, aninsulator 37 covering at least a part of the iron core 34, a wire 33winding around the iron core 34 and the insulator 37, and the moldedsection 32 made of a molding compound integrally molded with the ironcore 34, the insulator 37 and the wire 33. The molded section 32includes the internal molded section 32 a covering at least a part ofthe iron core 34 and the external molded section 32 b which is providedoutside the internal molded section 32 a and whose outermost portiondefines the outermost portion of the molded stator 31. A part of theinsulator 37 penetrates the external molded section 32 b so as to beexposed flush with the surface of the external section 32 b.

In the molded stator of this embodiment having such a configuration,since the insulator 37 has an exposed portion 37 a, the decomposingsolution is directly in contact with the exposed portion 37 a. Thus, theexposed portion 37 a is first decomposed and then decompositionsequentially proceeds to the inside of the insulator and the moldedsection 32 with ease. Thus, since a hollow is formed in the inside ofthe molded section, the molded section 32 is easily removed by anexternal mechanical impact, thus making it remarkably easy to separatethe wire 33 and the iron core 34.

The preferred embodiments of a molded motor of an exemplary moldedproduct of the present invention can be suitably combined. For example,the configuration of the insulator shown in FIG. 3 can be applied to themolded stator constituted by the molded section having the internalsection and the external section shown in FIG. 2, and can be applied tothe molded stator constituted by the single molded section shown in FIG.1.

The molded motor of an exemplary molded product of the present inventioncan be applied to a brushless direct current motor, an alternate currentmotor, a linear motor or the like.

The molded product of the present invention can be applied to aninsulator of a general motor (i.e., non-molded motor). In the case wherethe molded product of the present invention is used for the insulator ofthe motor, merely by immersing the motor in a decomposing solutiondescribed later, the insulator can be decomposed so as to be removed.For this reason, it is easy to separate and collect metals constitutingthe motor, and recycle of the metals is facilitated. Since the insulatorof the motor is generally formed thin, it is quite easily decomposed bythe decomposing solution. The application to such an insulator furtherhas the following advantages: Defectives which failed a conductivitytest before being molded in the production of the molded motor weredisposed as industrial waste in a state before being molded. This isbecause the removal of the insulator is difficult. By applying themolded product of the present invention to the insulator, it is possibleto remove the insulator simply by immersing the detectives in thedecomposing solution. As a result, an effective recycle of the metalsbecomes possible.

Furthermore, the molded product of the present invention can be appliedto the insulator of the conventional molded motor. In the case where themolded product of the present invention is used for the insulator of theconventional molded motor, an ordinary crushing treatment should beperformed to remove the molded section. However, a metal stripe afterbeing crushed and selected is immersed in the decomposing solution sothat the insulator which adheres to the metal stripe can be completelyremoved. Therefore a significantly better metal stripe can be collectedthan a conventional one.

Next, a recording medium which is another example of the molded productof the present invention will be described. Herein, a magnetic tape willbe described as an example of the recording medium.

FIG. 4 is a schematic partial cross sectional view of a magnetic tape.The magnetic tape 40 includes a substrate 41 and a recording layer 42formed on the substrate.

The substrate 41 can be formed using the aforementioned structurematerial of the present invention. In the case where the structurematerial of the present invention is used for the substrate of themagnetic tape, a content of a thermoplastic aromatic polyester in apolymer mixture of the thermoplastic aromatic polyester and athermoplastic aliphatic polyester is preferably 30 parts by weight orless on the basis of 100 parts by weight of the mixture. This is becausea substrate having a particularly excellent tensile strength can beobtained.

Any of known sheet forming methods can be employed as a method forforming the substrate, and not particularly limited. By forming theaforementioned structure material into a film having a desiredthickness, the substrate 41 can be obtained. Furthermore, after formingthe recording medium 42 described later on the substrate 41, theresultant substrate is cut in a desired width so as to obtain themagnetic tape 40. The thickness of the substrate can be varied dependingon the use, but preferably 4 to 10 μm.

The recording layer 42 is formed by a known method using a knownmagnetic recording material. Examples of the magnetic recording materialinclude iron oxide, chromium oxide, cobalt modified iron oxide, Baferrite and a cobalt-nickel alloy. Examples of the method for formingthe recording layer include a method in which a solution containingmagnetic recording material powder and a binder is applied to asubstrate and then dried; and a method such as evaporation andsputtering in which the recording layer is directly formed on thesubstrate.

Examples of the binder contained in the solution in the case where thesolution is applied include a vinyl chloride-vinyl acetate copolymer, avinyl chloride-acrylonitrile copolymer, nitrocellulose, thermoplasticaromatic polyester, thermoplastic aliphatic polyester, polyurethane,polyamide or the like. They can be used singularly or in combinationthereof. A binder containing a polymer mixture of thermoplastic aromaticpolyester and thermoplastic aliphatic polyester, or thermoplasticaliphatic polyester is preferable because it makes it easy to collectmagnetic recording material powder during decomposition. Examples of asolvent contained in the solution include methylethyl ketone,cyclohexanone, butyl acetate and toluene. They can be used singularly orin combination thereof. Furthermore, if necessary, the solution cancontain a surfactant; a dispersant such as a silane coupling agent: alubricant such as aliphatic amide, fluidized paraffin; an antistaticagent such as carbon black; and an abrasive such as aluminum and siliconcarbonate.

Furthermore, if necessary, the magnetic tape 40 can include an undercoatlayer between the substrate 41 and the recording layer 42, a backcoatlayer on the substrate surface in the opposite side of the recordinglayer, a topcoat layer on the surface of the recording layer or thelike.

Furthermore, in the case where the molded product is a magnetic tape(e.g., a music tape or a video tape), it is preferable that a housingsuch as a cartridge protecting the tape is formed of the structurematerial of the present invention. Since the housing is decomposed bythe decomposing solution, it is not necessary to separate the housing.As a result, the collection of the magnetic recording material isfurther facilitated.

C. Decomposing Solution

The polymer mixture contained in the structure material of the presentinvention can be decomposed into a monomer unit by a decomposingsolution comprising a base and a hydrophilic solvent. Thus, thedecomposition and the reduction in volume of the structure material ofthe present invention can be achieved. As a result, the reduction involume of the molded product of the present invention and the separationand collection of metals contained in the molded product can beachieved.

The base contained in the decomposing solution is dissociated in water(i.e., by contacting water) so as to generate a hydroxyl group. Examplesof such a base include a metal hydroxide such as a sodium hydroxide anda potassium hydroxide; a metal oxide such as a sodium oxide and acalcium oxide; a metal alkoxide such as sodium ethoxide and potassiumt-butoxide. They can be used singularly or in combination of two ormore. Sodium hydroxide is preferable in view of cost.

The base can be contained in the decomposing solution in the range of,preferably 0.1 to 50% by weight, more preferably 1 to 30% by weight, andmost preferably 2 to 20% by weight. In the case where the content isbelow 1% by weight, a catalyst effect during decomposition is low. Whenthe content exceeds 50% by weight, it is difficult to prepare thedecomposing solution. Furthermore, since the viscosity of thedecomposing solution becomes excessively high, permeability into thestructure material deteriorates, and thus decomposability deteriorates.

The hydrophilic solvent contained in the decomposing solution includeswater and an organic solvent having a satisfactory hydrophilicity withwater. Examples of the hydrophilic solvent include water; lower alcoholsuch as methanol, ethanol and isopropyl alcohol; glycol such as ethyleneglycol, propylene glycol, diethylene glycol; ketone such as acetone andmethylethyl ketone; ether such as dioxane and tetrahydrofuran. They canbe used singularly or in combination of two or more. Lower alcohol and amixed solvent of lower alcohol and water are preferable because theyhave excellent decomposability at room temperature. Particularlypreferred examples of lower alcohol include methanol and ethanol.

In the case where the mixed solvent of lower alcohol and water is usedas a hydrophilic solvent of the decomposing solution, water is containedin the mixing solvent in a range of, preferably 1 to 60% by weight, andmore preferably 3 to 50% by weight. When the content of water is notwithin such a range, a particularly excellent effect by mixing loweralcohol and water cannot sufficiently be obtained. Furthermore, in orderto maintain the particularly excellent effect by mixing lower alcoholand water, it is preferable that the content of water in the decomposingsolution is constantly within the above-mentioned range duringdecomposition. In other words, in the case where the decomposition takesa long time, or the decomposing solution is reused, it is preferable toadd water in a suitable amount. Specific examples of the mixed solventof lower alcohol and water are as follows: water and methanol (weightratio 50:50); water and ethanol (weight ratio 50:50); and water andethanol (weight ratio 95:5).

The decomposing solution can optionally contain an additive such as asurfactant, an anti-volatilizing agent and a preservative. By comprisingsuch an additive, it is possible to suitably adjust the characteristics(e.g., surface tension, volatilizability and prevervability) of thedecomposing solution. The content of the additive can be varieddepending on the type of the additive and a desired characteristic ofthe decomposing solution. Preferably, the additive can be contained inthe decomposing solution in an amount of 3% by weight or less.

D. A Decomposing Method for the Structure Material and the MoldedProduct of the Present Invention

A decomposing method for the structure material of the present inventionincludes the step of immersing the aforementioned structure material inthe decomposing solution at a temperature lower than the boiling pointof the decomposing solution.

A decomposing method for the molded product of the present inventionincludes the steps of immersing the molded product obtained by moldingthe structure material together with the metal in the decomposingsolution at a temperature lower than the boiling point of thedecomposing solution, and decomposing at least a part of the structurematerial forming the molded product, and then separating and collectingthe metals.

The immersion time can be varied depending on the temperature. Forexample, in the case of the immersion in the decomposing solution at 60°C., the period of time required for the decomposition treatment can beshortened up to about ⅙ of the period of the time in the case of theimmersion at room temperature. However, in order to prevent thehydrophilic solvent contained in the decomposing solution fromvolatilizing, it is desired that the temperature of the decomposingsolution be below the boiling point of the hydrophilic solvent.

In the case where the molded product is subjected to the decompositiontreatment, the separation and the collection of the metals is preferablyperformed in a state where the structure material remains moist. Whenthe structure material is dry, the mechanical strength of the structurematerial becomes large, thus making it difficult to separate and collectthe metals. Furthermore, the collection of the metals is preferablyperformed after the base contained in the decomposing solution isremoved by washing. This is to ensure safety to the person involved. Thewashing is preferably performed using water and/or a hydrophilicsolvent.

E. Function

The structure material of the present invention comprises a polymermixture of a thermoplastic aromatic polyester and a thermoplasticaliphatic polyester, and the content of the thermoplastic aromaticpolyester in the polymer mixture is larger than the content of thethermoplastic aliphatic polyester. For this reason, the structurematerial of the present invention has a structure where thethermoplastic aliphatic polyester in the form of particles are dispersedin the thermoplastic aromatic polyester. Analyzing the dispersingstructure, the particles of the thermoplastic aliphatic polyester has aparticle diameter on the order of several 10 μm or less, and particleshaving a particle diameter on the order of 100 μm do not substantiallyexist. In other words, the structure material of the present inventionhas a very fine-dispersed structure. Therefore, in the structurematerial of the present invention, an ester bond portion of thethermoplastic aromatic polyester and an ester bond portion of thethermoplastic aliphatic polyester can exist very closely. In addition,the portion where these ester bond portions exist closely can existuniformly over the entire structure material.

On the other hand, the ester bond portion of the thermoplastic aliphaticpolyester can be easily decomposed by the decomposing solutioncontaining a base and a hydrophilic solvent. In other words, thedecomposing solution permeates the structure material toward the esterbond portion of the thermoplastic aliphatic polyester. When thedecomposing solution permeates the structure material and contacts theester bond portion of the thermoplastic aliphatic polyester, thesolution can also contact the ester bond portion of the aromaticpolyester existing close to the ester bond portion of the aliphaticpolyester. More specifically, by dispersing the aliphatic polyester inthe aromatic polyester, the decomposing solution, which does notpermeate inside in the case of the aromatic polyester alone, permeatesand contacts the ester bond portion of the aromatic polyester. As aresult, the aromatic polyester which is not decomposed when it is usedalone is decomposed by the decomposing solution. Therefore, thestructure material of the present invention can be decomposed easily bythe decomposing solution while maintaining the mechanical strength andthe heat resistance of the aromatic polyester.

Furthermore, generally, since the melting point of the thermoplasticaliphatic polyester is lower than that of the thermoplastic aromaticpolyester, the shrinkage of the structure material by natural coolingafter being molded can be prevented. In other words, the thermoplasticaliphatic polyester can function as a low shrink agent. For this reason,since the shrinkage of the structure material of the present inventionafter being molded is small, the shape and size of the molded productcan be controlled precisely. Thus, the structure material of the presentinvention has excellent moldability.

As described above, the structure material of the present invention canbe decomposed easily by the decomposing solution containing a base and ahydrophilic solvent. The decomposition is promoted by heating, but theheating temperature is at most below the boiling point of thehydrophilic solvent. In other words, the structure material of thepresent invention requires a significantly small quantity of heat fordecomposition, compared with the conventional structure materialrequiring burning. Therefore, the change in the characteristics ofvaluable substances such as metals contained in the structure materialis significantly small, the structure material of the present inventionis very useful in view of recycling the valuable substances.Furthermore, The structure material of the present invention which doesnot require burning is very useful in view of the environment issues andthe energy issues.

The molded product of the present invention which is molded using theaforementioned structure material can be decomposed easily by thedecomposing solution containing a base and a hydrophilic solventaccording to the above-described mechanism. Such advantages of themolded product of the present invention are provided in the case of themolded product containing metals. More specifically, the molded productof the present invention does not require burning or a crushingtreatment unlike the conventional one. Therefore, since valuable metalsare separated easily and collected, the molded product of the presentinvention is very useful with respect to recycling. Furthermore, by thedecomposition of the structure material, the volume of the moldedproduct can be reduced significantly. Thus, the molded product of thepresent invention is excellent in view of the reduction in volume ofwaste.

EXAMPLES Example 1

Eighty parts by weight of polyethylene terephthalate (hereinafter,referred to as PET) represented by Formula (I) (DIANITE manufactured byMitsubishi Rayon Co., Ltd.), which is a thermoplastic aromaticpolyester, was melted by a kneader heated to 280° C. Then, 20 parts byweight of polycaprolactone represented by Formula (V) (having amolecular weight of 40,000; PLACCELL manufacture by Daicel ChemicalIndustries, Ltd.), which is a thermoplastic aliphatic polyester, wasmixed thereto, and the mixture was kneaded for about 15 minutes toobtain a structure material.

The obtained structure material was formed into a plate about 1 mm thickat about 250° C. The obtained plate-like molded product was cut intorectangular parallelepipeds having a size of 10 mm×20 mm×1 mm to obtaina sample for decomposition tests.

On the other hand, 16 parts by weight of sodium hydroxide was dissolvedin 100 parts by weight of water to prepare a decomposing solution. Then,30 cc of the decomposing solution and the sample obtained above wereplaced in an air-tight stainless container, and the content was stirredat 80° C. for 110 hours. After the completion of the stirring, areduction of the weight of the sample was measured to evaluatedecomposability. The results of the decomposition test are shown inTable 1, together with the results of Examples 2 to 4 and ComparativeExample 1 described later.

TABLE 1 Weight reduction of sample (%) Example 1 40.2 Example 2 38.6Example 3 21.0 Example 4 17.7 Comparative Example 1 3.0

As is apparent from Table 1, the reduction in the weight of the samplewas about 40%, which was about twice the added amount of thethermoplastic aliphatic polyester. In other words, it was found out thatat least about 20% of the thermoplastic aromatic polyester wasdecomposed. Therefore, it was determined that, by mixing thethermoplastic aliphatic polyester, the decomposition of thethermoplastic aromatic polyester is promoted significantly. Furthermore,the sample after the completion of the decomposition test had partiallycracked, which makes it apparent that the separation of metals is easyin the case where the molded product contains the metals.

Furthermore, the decomposing solution after the completion of thedecomposition test was neutralized with hydrochloric acid, and aprecipitate generated in this case was examined by infraredspectroscopy. As a result, isophthalic acid and ethylene glycol weredetected, and this indicates that the thermoplastic aromatic polyesteris decomposed into a monomer unit. In other words, the structurematerial of the present invention is useful to collect and reuseisophthalic acid and ethylene glycol.

Example 2

A structure material was obtained in the same manner as in Example 1,except that 20 parts by weight of polylactic acid (LACTY manufactured byShimadzu Corporation) represented by Formula (VI) was used instead of 20parts by weight of polycaprolactone. Subsequently, the same procedure asin Example 1 was performed to prepare a sample for a decomposition testand the sample was subjected to the decomposition test in the samemanner as in Example 1. The results are shown in Table 1. As a result,it was found that the decomposition of the thermoplastic aromaticpolyester is promoted significantly as in Example 1. The sample afterthe completion of the decomposition test had partially cracked as inExample 1. Furthermore, as a result of infrared spectroscopy which wasperformed in the same manner as in Example 1, isophthalic acid andethylene glycol were detected, and this indicates that the thermoplasticaromatic polyester was decomposed into a monomer unit.

Example 3

PET and polycaprolactone were moltened and kneaded in the same manner asin Example 1. Then, 100 parts by weight of heavy calcium carbonatehaving an average diameter of 20 μm (manufactured by Maruo Calcium Co.,Ltd.) was added to the molten and kneaded product, and the resultantmixture was kneaded for about 10 minutes to obtain a structure material.Subsequently, the same procedure as in Example 1 was performed toprepare a sample for a decomposition test and the sample was subjectedto the decomposition test in the same manner as in Example 1. Theresults are shown in Table 1.

As is apparent from Table 1, the reduction in the weight of the samplewas about half of that in Examples 1 and 2. This is because calciumcarbonate was not decomposed. The strength of the sample after thecompletion of the test deteriorated so significantly that the surfacewas detached easily with bare hands. Thus, it is apparent that in thecase where the molded product contains metals, the separation of themetals is easy, even if a filler is added in order to improve themechanical strength.

Furthermore, as a result of infrared spectroscopy which was performed inthe same manner as in Example 1, isophthalic acid and ethylene glycolwere detected, and this indicates that the thermoplastic aromaticpolyester is decomposed into a monomer unit.

Example 4

PET and polycaprolactone were kneaded in the same manner as inExample 1. Then, 100 parts by weight of heavy calcium carbonate havingan average diameter of 20 μm (manufactured by Maruo Calcium Co., Ltd.)and 30 parts by weight of glass fibers having a length of 20 mm weresequentially added to the molten and kneaded product, and the resultantmixture was kneaded for about 15 minutes to obtain a structure material.Subsequently, the same procedure as in Example 1 was performed toprepare a sample for a decomposition test and the sample was subjectedto the decomposition test in the same manner as in Example 1. Theresults are shown in Table 1.

As is apparent from Table 1, the reduction in the weight of the samplewas about the same extent as that in Example 3. The strength of thesample after the completion of the test deteriorated so significantlythat the surface was detached easily with bare hands, as in Example 3.Thus, it is apparent that in the case where the molded product containsmetals, the separation of the metals is easy, even if a filler is addedin order to improve mechanical strength.

Furthermore, as a result of infrared spectroscopy which was performed inthe same manner as in Example 1, large amounts of isophthalic acid andethylene glycol were detected, and this indicates that the thermoplasticaromatic polyester was decomposed into a monomer unit.

Comparative Example 1

A structure material was obtained in the same manner as in Example 1,except that only PET was used. Subsequently, the same procedure as inExample 1 was performed to prepare a sample for a decomposition test andthe sample was subjected to the decomposition test in the same manner asin Example 1. The results are shown in Table 1.

As is apparent from Table 1, the weight of the sample was reduced byonly 3% by weight. Furthermore, as a result of infrared spectroscopywhich was performed in the same manner as in Example 1, only smallamounts of isophthalic acid and ethylene glycol were detected. In otherwords, it was found that the structure material of Comparative Example 1was only decomposed in a minute amount, and was not decomposed to suchan extent that it structurally collapsed.

Example 5

The decomposability of the structure material was evaluated in the samemanner as in Example 1, except that the decomposition test was performedat 100° C. As a result, the weight of the sample for the decompositiontest was reduced to the same extent as in Example 1 (i.e., about 40% byweight) in as short as about 30 hours. This indicates that by heatingthe decomposing solution, the decomposition rate becomes significantlyhigh.

Example 6

The same structure material as used in Example 3 was used to form aplate-like molded product having a size of 20 mm×40 mm×7 mm, and thismolded product was used as a sample for a decomposition test. The samplewas immersed in the same decomposing solution as in Example 1 to athickness of 1 mm in its thickness direction. The decomposability wasevaluated by the level of softness of the sample after 100 hours andafter 500 hours. The level of the softness was evaluated by thethickness of the softened portion from the surface of the sample in theimmersed side.

As a result, the sample was softened to a thickness of about 3 mm fromthe surface of the sample in the immersed side after 100 hours, andsubstantially the entire sample (about 7 mm from the surface of thesample in the immersed side) was softened after 500 hours.

Example 7

A sample for a decomposition test was prepared in the same manner as inExample 6, except that 200 parts by weight of heavy calcium carbonatewas used, and the decomposability thereof was evaluated.

As a result, the sample was softened to a thickness of about 3 mm fromthe surface of the sample in the immersed side after 100 hours, andsubstantially the entire sample (about 7 mm from the surface of thesample in the immersed side) was softened after 500 hours.

Example 8

A sample for a decomposition test was prepared in the same manner as inExample 6, except that 400 parts by weight of heavy calcium carbonatewas used, and the decomposability thereof was evaluated.

As a result, the sample was softened to a thickness of about 2 mm fromthe surface of the sample in the immersed side after 100 hours, andsubstantially the entire sample (about 7 mm from the surface of thesample in the immersed side) was softened after 500 hours.

Comparative Example 2

A sample for a decomposition test was prepared in the same manner as inExample 6, except that 500 parts by weight of heavy calcium carbonatewas used, and the decomposability thereof was evaluated.

As a result, the sample was softened only to a thickness of about 1 mmfrom the surface of the sample in the immersed side after 500 hours.

Example 9

A sample for a decomposition test was prepared in the same manner as inExample 1. On the other hand, as shown in Table 2, 30 parts by weight ofethanol and 1.25 parts by weight of sodium hydroxide were mixed toprepare a decomposing solution. The sample was immersed in the obtaineddecomposing solution at room temperature for 15 hours. A reduction inthe weight of the sample after the immersion was measured to evaluatethe decomposability. The results are shown in Table 3, together with theresults of Example 10 and Comparative Example 3, which are describedlater.

TABLE 2 Sodium hydroxide Water Ethanol Example 9 1.25 0 30 Example 101.25 6 24 Comparative 0.00 6 24 Example 3 (Unit: Part by weight)

TABLE 3 Weight reduction of sample (%) Example 9 35.2 Example 10 64.5Comparative Example 3 0.0

As is apparent from Table 3, the weight reduction of the sample wasabout 35% by weight, and it was found that the structure material of thepresent invention was satisfactorily decomposed by the decomposingsolution. Furthermore, the volume of the sample was significantlyreduced, and it was found that the structure material of the presentinvention was useful in view of the reduction in volume of waste.

Example 10

The decomposability of the structure material was evaluated in the samemanner as in Example 9, except that the decomposing solution shown inTable 2 was used. The results are shown in Table 3.

As is apparent from Table 3, the weight reduction of the sample wasabout 65% by weight, which is about twice the reduction in Example 9.This revealed that, by using a mixed solvent of a base and a hydrophilicsolvent, the decomposition of the structure material was significantlypromoted. Furthermore, the volume of the sample was significantlyreduced, and it was found that the structure material of the presentinvention was useful in view of the reduction in volume of waste.

Comparative Example 3

The decomposability of the structure material was evaluated in the samemanner as in Example 9, except that the decomposing solution as shown inTable 2 was used and the sample was immersed at 80° C. The results areshown in Table 3.

As is apparent from Table 3, in spite of heating to 80° C., the sample(i.e., the structure material) was not substantially decomposed.

Example 11

The decomposability was evaluated in the same manner as in Example 10,except that methanol was used instead of ethanol. As a result, as inExample 10, the structure material was significantly decomposed.Furthermore, the volume of the structure material was significantlyreduced.

Example 12

A sample for a decomposition test was prepared in the same manner as inExample 3. Subsequently, the same procedure as in Example 9 wasperformed to evaluate the decomposability. As a result, as in Example 9,the structure material was significantly decomposed. Furthermore, thevolume of the structure material was significantly reduced.

Example 13

The decomposability was evaluated in the same manner as in Example 9,except that the sample was immersed at 60° C. As a result, the weight ofthe sample was reduced by about 35% in 2 hours after immersion. Thisindicates that the decomposition of the structure material wassignificantly promoted by heating.

Example 14

The decomposability was evaluated in the same manner as in Example 10,except that the sample was immersed at 60° C. As a result, the weight ofthe sample was reduced by about 65% in 2 hours after immersion. Thisindicates that the decomposition of the structure material wassignificantly promoted by heating, as in Example 13.

Comparative Example 4

A sample for a decomposition test was prepared in the same manner as inComparative Example 1. The decomposability was evaluated in the samemanner as in Example 9, except that the sample was immersed at 80° C.The results revealed that the weight of the sample was not substantiallychanged, and the structure material was not substantially decomposed.

Comparative Example 5

A sample for a decomposition test was prepared in the same manner as inComparative Example 1. The decomposability was evaluated in the samemanner as in Example 10, except that the sample was immersed at 80° C.The results revealed that the weight of the sample was not substantiallychanged, and the structure material was not substantially decomposed.

Example 15

A structure material was obtained in the same manner as in Example 1.The structure material was integrally molded with an iron core wound bya wire which is an enamelled wire to produce a molded motor as shown inFIG. 1. The maximum thickness of the molded section was 5 mm.

On the other hand, 24 parts by weight of ethanol, 6 parts by weight ofwater and 1.25 parts by weight of sodium hydroxide were mixed to preparea decomposing solution. The molded motor produced in the above-mentionedmanner was immersed in the decomposing solution at 60° C. for 10 hours.As a result, the molded section (i.e., the structure material) wassubstantially decomposed, and the wire and the iron core were completelyseparated.

Example 16

A structure material was obtained in the same manner in Example 2.Subsequently, the same procedure as in Example 15 was performed toproduce a molded motor and to immerse the molded motor in thedecomposing solution. As a result, the molded section (i.e., thestructure material) was substantially decomposed, and the wire and theiron core were completely separated.

Example 17

A structure material was obtained in the same manner in Example 3.Subsequently, the same procedure as in Example 15 was performed toproduce a molded motor and to immerse the molded motor in thedecomposing solution. As a result, the molded section (i.e., thestructure material) slightly remained, but the molded section was easilyremoved simply by tapping the surface thereof with a hammer. Then, thewire and the iron core were completely separated.

Furthermore, calcium carbonate contained in the structure material wasseparated. This indicates that the structure material of the presentinvention is useful in view of the reuse of an inorganic filler.

Example 18

A structure material was obtained in the same manner in Example 4.Subsequently, the same procedure as in Example 15 was performed toproduce a molded motor and to immerse the molded motor in thedecomposing solution. As a result, the molded section (i.e., thestructure material) slightly remained, but the molded section wasremoved easily simply by tapping the surface thereof with a hammer.Then, the wire and the iron core were completely separated.

Furthermore, calcium carbonate and glass fibers contained in thestructure material were separated also. This indicates that thestructure material of the present invention is also useful in view ofthe reuse of an inorganic filler and the glass fibers. Especially, withrespect to the glass fibers, since the glass fibers have not beensubjected to a crushing treatment or heating at a high temperature, suchglass fibers can be reused in an excellent state without nocharacteristic change or break.

Comparative Example 6

A structure material was obtained in the same manner in ComparativeExample 1. Subsequently, the same procedure as in Example 15 wasperformed to produce a molded motor and to immerse the molded motor inthe decomposing solution. The molded section (i.e., the structurematerial) was not decomposed to a great extent, and when the surface ofthe molded section was tapped with a hammer, the surface was onlyslightly detached, but the wire and the iron core were not separatedfrom the molded section.

Comparative Example 7

A molded motor was produced in the same manner as in Example 15, exceptthat polycaprolactone alone was used as the structure material. However,in the molded motor,the mechanical strength of the molded section wasextremely low, and it was impossible to put it into practical use as amolded motor.

Comparative Example 8

A molded motor was produced in the same manner as in Example 15, exceptthat polylactic acid alone was used as the structure material. However,in the molded motor, as in Comparative Example 7, the mechanicalstrength of the molded section was extremely low, and it was impossibleto put it into practical use as a molded motor.

Example 19

A structure material was obtained in the same manner as in Example 1.The structure material and an iron core wound by a wire via thestructure material were subjected to pressure molding at about 250° C.in such a manner that the structure was not deformed, so as to form aninternal molded section. The maximum thickness of the internal moldedsection was about 2 mm.

On the other hand, 70 parts by weight of unsaturated polyester resin(EPOLAC manufactured by Nippon Shokubai Co., Ltd.) containingunsaturated polyester represented by Formula (XIII), 30 parts by weightof styrene, 1 part by weight of t-butylperoxybenzoate (PERBUTYL Zmanufactured by Nippon Oil and Fats Co., Ltd.), 200 parts by weight ofheavy calcium carbonate (Maruo Calcium Co., Ltd.) having an averagediameter of 20 μm and 30 parts by weight of glass fibers having a lengthof 20 mm were mixed to prepare a molding compound for forming anexternal molded section.

The iron core where the internal molded section was formed and themolding compound for forming an external molded section were integrallymolded to form the external molded section. Thus, a molded motor asshown in FIG. 2 was produced. The maximum thickness of the externalmolded section was about 6 mm.

After a part of the external molded section of the obtained molded motorwas exposed by cutting the external molded section, the molded motor wasimmersed in a decomposing solution containing 24 parts by weight ofethanol, 6 parts by weight of water and 1.25 parts by weight of sodiumhydroxide at room temperature for 48 hours. As a result, the internalmolded section was almost decomposed, and a hollow portion was formedbetween the external molded section and the iron core and the wire.Thus, the iron core and the wire was separated and collected easily.

Example 20

Polybutylene terephthalate (hereinafter, referred to as PBT) representedby Formula (II) (TUFPET manufactured by Mitsubishi Rayon Co., Ltd.) wasused as a thermoplastic aromatic polyester. Polylactic acid (LACTYmanufactured by Shimadzu Corporation) represented by Formula (VI) wasused as a thermoplastic aliphatic polyester. Eighty parts by weight ofthe PBT and 20 parts by weight of the polylactic acid were moltened andkneaded by a biaxial extruder at 240° C. so as to obtain a structurematerial. The structure material was formed into a form where athickness thereof was about 1 mm and the iron core could be disposed inthe inside thereof. The iron core was disposed in the inside of themolded product, and was wound by an enamelled wire on its circumference.Thus, the iron core wound by a wire via an insulator (hereinafter,referred to as a stator) was produced.

On the other hand, 1 part by weight of sodium hydroxide and 25 parts byweight of water were mixed to prepare a decomposing solution. Theobtained stator was immersed in the decomposing solution at 80° C. As aresult, the insulator (i.e., the structure material) was decomposed andremoved in about 70 hours. Thus, the iron core and the wire wereseparated and collected.

Example 21

A molded motor was produced in the same manner as in Example 20. Themolded motor was crushed by a shredder and the debris were selected sothat low-quality metals (iron core and wire) to which an insulator wasattached in large quantity were collected. The low-quality metals wereimmersed in a decomposing solution containing 24 parts by weight ofethanol, 6 parts by weight of water and 1.25 parts by weight of sodiumhydroxide at room temperature for 50 hours. Then, a treatment wasperformed by a rolling mixer for about 1 hour. As a result, extremelyhigh-quality metals from which the insulator was completely removed werecollected.

Example 22

A stator was produced in the same manner as in Example 20, except that90 parts by weight of PBT and 10 parts by weight of polybutylenesuccinate represented by Formula (X) (BIONOLLE manufactured by ShowaHigh Polymer Co., Ltd.) were used as a structure material. Subsequently,the same procedure as in Example 20 was performed and the stator wasimmersed in the decomposing solution at 80° C. As a result, theinsulator (i.e., the structure material) was decomposed and removed inabout 150 hours. Thus, the iron core and the wire were separated andcollected.

Example 23

Seventy parts by weight of unsaturated polyester resin (EPOLACmanufactured by Nippon Shokubai Co., Ltd.) containing unsaturatedpolyester represented by Formula (XIII), 30 parts by weight of styrene,1 part by weight of t-butylperoxybenzoate (PERBUTYL Z; manufactured byNippon Oil and Fats Co., Ltd.) as a curing agent, 200 parts by weight ofheavy calcium carbonate (manufactured by Maruo Calcium Co., Ltd.) havingan average diameter of 20 μm and 30 parts by weight of glass fibershaving a length of 20 mm were mixed to prepare a molding compound forforming a molded section.

The structure material of Example 20 was used for an insulator. An ironcore wound by a wire via the insulator and the molding compound forforming the molded section were integrally molded so that the insulatorwas exposed flush with the surface of the molded product. Thus, a moldedmotor as shown in FIG. 3 was produced.

This molded motor was immersed in the decomposing solution of Example 20at 80° C. for 200 hours. As a result, the insulator (i.e., the structurematerial) was dissolved and a hollow was formed between the moldedsection and the iron core and the wire. Thus, the iron core and the wirewere readily separated and collected.

Example 24

Eighty-five parts by weight of polybutylene terephthalate (TUFPETmanufactured by Mitsubishi Rayon Co., Ltd.) and 15 parts by weight ofpolybutylene succinate (BIONOLLE manufactured by Showa High Polymer Co.,Ltd.) were moltened and kneaded by an extruder at 250° C. so as toobtain a structure material. The structure material was heated at 250°C. and pressurized to be formed into a sheet having a thickness of 50μm. Thus, a substrate was produced. A Co—Ni alloy (70/30) as a recordingmaterial was deposited to a thickness of 0.2 μm on the substrate under avacuum to form a recording layer. The sheet on which the recording layerwas formed was cut into stripes having a width of 4 mm to obtain amagnetic tape.

The obtained magnetic tape was immersed in an aqueous solution of 5% byweight of sodium hydroxide at 80° C. for 2 hours. As a result, thesubstrate was completely decomposed and only a recording layer was leftin the decomposing solution. Thus, the valuable recording material wasseparated and collected.

Comparative Example 9

A magnetic tape was prepared in the same manner as in Example 24, exceptthat the substrate was composed of polyethylene terephthalate alone.Then, the magnetic tape was immersed in the decomposing solution. As aresult, the substrate cracked so slightly that the recording materialcould not be separated nor collected.

Industrial Applicability

As described above, the present invention provides: (1 ) a structurematerial which has excellent mechanical strength and heat resistance,and is decomposed easily at the time of disposal; (2 ) a structurematerial having excellent moldability; (3) a molded product which hasexceptional mechanical strength and heat resistance, and is decomposedeasily at the time of disposal; (4) a molded product from which valuablemetals are collected easily; (5) a molded product which is easilyreduced in volume; (6) a useful molded product in view of environmentalissues and energy issues; (7) a useful molded product in view ofrecycling; and (8) a simple and easy method for decomposing such astructure material and such a molded product.

What is claimed is:
 1. A structure material consisting essentially of 20parts by weight or more of a polymer mixture on the basis of 100 partsby weight of the structure material, wherein the polymer mixtureconsists essentially of (A) a thermoplastic aromatic polyester; and (B)a thermoplastic aliphatic polyester, wherein a content of thethermoplastic aromatic polyester in the polymer mixture is larger than acontent of the thermoplastic aliphatic polyester, wherein thethermoplastic aromatic polyester is obtained bycondensation-polymerizing at least one aromatic polybasic acid and atleast one glycol, and the at least one aromatic polybasic acid isselected from the group consisting of phthalic anhydride, isophthalicacid, terphthalic acid, diphenyl carboxylic acid and combinationsthereof, and the at least one glycol is selected from the groupconsisting of ethylene glycol, propylene glycol, diethylene glycol,dipropylene glycol, neopentyl glycol, hexamethylene glycol, polyethyleneglycol, butanediol and combinations thereof, wherein the thermoplasticaliphatic polyester is at least one selected from the group consistingof polycaprolactone, polycaprolactone diol, polycaprolactone triol,polyethylene succinate, polybutylene succinate, and polylactic acid,wherein the polymer mixture comprises 3 to 40 parts by weight of thealiphatic polyester on the basis of 100 parts by weight of the polymermixture, and wherein the polymer mixture can be decomposed into amonomer unit by a decomposing solution containing a base and ahydrophilic solvent.
 2. A molded product formed of a structure material,wherein the structure material consisting essentially of 20 parts byweight or more of a polymer mixture on the basis of 100 parts by weightof the structure material, wherein the polymer mixture consistsessentially of (A) a thermoplastic aromatic polyester; and (B) athermoplastic aliphatic polyester, and a content of the thermoplasticaromatic polyester in the polymer mixture is larger than a content ofthe thermoplastic aliphatic polyester, and wherein the thermoplasticaromatic polyester is obtained by condensation-polymerizing at least onearomatic polybasic acid and at least one glycol, and the at least onearomatic polybasic acid is selected from the group consisting ofphthalic anhydride, isophthalic acid, terephthalic acid, diphenylcarboxylic acid and combinations thereof, and the at least one glycol isselected from the group consisting of ethylene glycol, propylene glycol,diethlylene glycol, dipropylene glycol, neopentyl glycol, hexamethyleneglycol, polyethylene glycol, butanediol and combinations thereof,wherein the thermoplastic aliphatic polyester is at least one selectedfrom the group consisting of polycanrolactone, polycaprolactone diol,polycaprolactone triol, polyethylene succinate, polybutylene succinateand polylactic acid, wherein the polymer mixture comprises 3 to 40 partsby weight of the aliphatic polyester on the basis of 100 parts by weightof the polymer mixture, and wherein the polymer mixture can bedecomposed into a monomer unit by a decomposing solution containing abase and a hydrophilic solvent.
 3. A molded product according to claim2, being a recording medium comprising a substrate formed of thestructure material and a recording layer provided on the substrate.
 4. Amolded product according to claim 2, being selected from the groupconsisting of a magnetic tape, a magnetic disc, an opto-magnetic discand a phase change type optical disc.
 5. A molded product according toclaim 2, being formed by molding the structure material together with atleast a metal.
 6. A molded product according to claim 5, being a moldedmotor having a molded section formed of the structure materialintegrally molded containing the metal, the structure materialcontaining an inorganic filler.
 7. A molded product according to claim6, wherein the molded section includes an internal molded sectioncovering the metal and an external molded section which is providedoutside the internal molded section and whose outermost portion definesan outermost portion of the molded product, the internal molded sectionbeing formed of the structure material, the external molded sectionbeing formed of a molding compound containing a thermosetting resin. 8.A molded product according to claim 5, being a molded motor having amolded section formed of the structure material integrally moldedcontaining the metal and an insulator, a part of the insulatorpenetrating the molded section and being exposed flush with the surfaceof the molded section.
 9. A molded product according to claim 8, themolded section being formed of a molding compound containing athermosetting resin, the insulator comprising 20 parts by weight or moreof a polymer mixture of a thermoplastic aromatic polyester and athermoplastic aliphatic polyester on the basis of 100 parts by weight ofthe insulator, the aliphatic polyester being at least one selected fromthe group consisting of polycaprolactone, polycaprolactone diol,polycaprolactone triol, polyethylene succinate, polybutylene succinateand polylactic acid.
 10. A decomposing method for a structure material,wherein the structure material consisting essentially of 20 parts byweight or more of a polymer mixture on the basis of 100 parts by weightof the structure material, wherein the polymer mixture consistsessentially of (A) a thermoplastic aromatic polyester; and (B) athermoplastic aliphatic polyester, and a content of the thermoplasticaromatic polyester in the polymer mixture is larger than a content ofthe thermoplastic aliphatic polyester, wherein the thermoplasticaromatic polyester is obtained by condensation-polymerizing at least onearomatic polybasic acid and at least one glycol, and the at least onearomatic polybasic acid is selected from the group consisting ofphthalic anhydride isophthalic acid terephthalic acid, diphenylcarboxylic acid and combinations thereof, and the at least one glycol isselected from the group consisting of ethylene glycol, propylene glycol,diethylene glycol, dipropylene glycol, neopentyl glycol, hexamethyleneglycol, polyethylene glycol, butanediol and combinations thereof,wherein the thermoplastic aliphatic polyester is at least one selectedfrom the group consisting of polycaprolactone, polycaprolactone diol,polycaprolactone triol, polyethylene succinate, polybutylene succinateand polylactic acid, and wherein the polymer mixture comprises 3 to 40parts by weight of the aliphatic polyester on the basis of 100 parts byweight of the polymer mixture, the method comprising the step ofimmersing the structure material in a decomposing solution containing abase and a hydrophilic solvent at a temperature lower than the boilingpoint of the hydrophilic solvent.
 11. A decomposing method for a moldedproduct formed by molding a structure material together with at least ametal, wherein the structure material consisting essentially of 20 partsby weight or more of a polymer mixture on the basis of 100 parts byweight of the structure material, wherein the polymer mixture consistsessentially of (A) a thermoplastic aromatic polyester; and (B) athermoplastic aliphatic polyester, and a content of the thermoplasticaromatic polyester in the polymer mixture is larger than a content ofthe thermoplastic aliphatic polyester, wherein the thermoplasticaromatic polyester is obtained by condensation-polymerizing at least onearomatic polybasic acid and at least one glycol, and the at least onearomatic polybasic acid is selected from the group consisting ofphthalic anhydride, isophthalic acid, terephthalic acid, diphenylcarboxylic acid and combinations thereof, and the at least one glycol isselected from the group consisting of ethylene glycol, propylene glycol,diethylene glycol, dipropylene glycol, neopentyl glycol, hexamethyleneglycol, polyethylene glycol, butanediol and combinations thereof,wherein the thermoplastic aliphatic polyester is at least one selectedfrom the group consisting of polycaprolactone, polycaprolactone diol,polycaprolactone triol, polyethylene succinate, polybutylene succinateand polylactic acid, wherein the polymer mixture comprises 3 to 40 partsby weight of the aliphatic polyester on the basis of 100 parts by weightof the polymer mixture, the method comprising the steps of: immersingthe molded product in a decomposing solution containing a base and ahydrophilic solvent at a temperature lower than the boiling point of thehydrophilic solvent, and decomposing at least a part of the structurematerial forming the molded product and then separating and collectingthe metal.
 12. A method according to claim 11, wherein the hydrophilicsolvent is a mixed solvent of water and lower alcohol.
 13. A methodaccording to claim 11, wherein the separation and collection of themetal is preformed in a state where the structure material remainsmoist.